So I am thinking about a 70-200mm lens for my C100. I would love to hear thoughts about the differences between the version that only goes to f4 vs. f2.8. The f4 is of course less expensive. Also with shooting video I assume the Image Stabilization becomes more important than with stills.

Primary use would be for corporate/commercial shoots in a little more controlled situations than reality or documentary. So I assume I could add a little light to make the difference of f4 vs. f2.8 possibly less of an issue.

I've found that with a Super35 size sensor I rarely go handheld with the 70-200 for corporate of commercial type shoots - So IS for me would be more a stills issue since for video I'm on a tripod with that lens. On the other hand I often appreciate the softer backgrounds I get with the 2.8.
When you say 'add more light' for corporate things, you may really be saying 'add more gain' -- since often you'll be doing interviews in large office spaces where you are emphasizing the depth in the background - but there is no way you will be lighting 200+ feet of background depth - so you are lighting your foreground to look better but match the light level of the background -- thus you will be using gain to adjust your exposure level if you are shooting wide open. Hence my preference for the 2.8
Also, if you do multi-camera interview shoots, you probably want to have your apertures consistent across your different cameras/lenses.

I have the f4 IS. Sometimes I'd like the extra stop, but pushing the ISO is a good solution with these cameras. The size/weight advantage and sharpness wide open makes it the best choice for video, I'd say. In fact, I often find it a bit too sharp for faces.

The *only* reason I did that, was because I found myself using that lens for a lot of handheld still photography.

For shooting video, I'd only use it only with a tripod, not handheld. And in that case the non-IS version is just fine. Plus, it's a bargain at just about 50% the cost of the IS version. In fact, it's one of the least (if not *the* least) expensive L-series lenses in the Canon line.

Now as far as the f/2.8 goes, I recognize how popular it is. You see them everywhere and for good reason. But I don't think I'll ever have one. It's just so dang heavy. The f/4 is a breeze to walk around with, while the f/2.8 is a tank.

All four of those lenses are just excellent. Optically I think they're equally sharp especially since the second-generation f/2.8 came out. If you shoot primarily indoors then the f/2.8 is the better way to go. But if you're primarily shooting outdoors then the f/4 is plenty good and you save some coin.

There's also the 70-300 "white lens" to further complicate matters. It's f/4 at 200mm then stops down to f/5.6 at 300mm. It's about the same price as the 70-200 f/2.8 non-IS.

I've been shooting with the 70-200 2.8 IS II for a year now. It's my favorite lens I own. The F4 is slightly sharper, but the 2.8 has better bokeh. The 70-200 is a tank but I use it on sticks only so it's fine. I shoot stills handheld with it though and it's a little big and heavy but I love shooting with it.

I know three people who bought the F4 IS and regret not stepping up to the plate for the 2.8 IS. If I only shot tripod mounted video with it, I would skip the IS version, but it's useful for stills. If you shoot mostly exteriors, F4 would be a good choice but if you spend time shooting in existing light interiors, 2.8 all day, every day over the F4. I don't care what anyone says, adding gain is not as good as having a faster lens. Grain is grain, you can rationalize it all you want but images with my C200 at ISO 2000 don't look as good as the native ISO 800 as far as grain.

I know three people who bought the F4 IS and regret not stepping up to the plate for the 2.8 IS.

I have considered upgrading to the 2.8, mostly for shoots in which I can't control the lighting (which happens). However, the elephant in the room is that new 70-200 f/4 Cine-Servo. I have the 18-80, and 70-200 is more of the focal length I want servo for, but at this point it doesn't make sense to own both, so I'm conflicted.

Plus, the 2.8 L II is much bigger, even when not being used. As an example, I need a telephoto in November for a seven day shoot in Vegas, and I have to transport that via plane, ideally in carry-on.

I have considered upgrading to the 2.8, mostly for shoots in which I can't control the lighting (which happens). However, the elephant in the room is that new 70-200 f/4 Cine-Servo. I have the 18-80, and 70-200 is more of the focal length I want servo for, but at this point it doesn't make sense to own both, so I'm conflicted.

Plus, the 2.8 L II is much bigger, even when not being used. As an example, I need a telephoto in November for a seven day shoot in Vegas, and I have to transport that via plane, ideally in carry-on.

I have to be honest and say that while I think the 70-200 2.8 IS II is a great lens that can make amazing images, a side benefit is the look of the lens on the camera, clients like seeing "the big glass" when we are working with celebrities and talent.

I just wrote a small article about working with a Canon CN-E 70-200 T4.4 prototype for HD Video Pro for several client shoots. It's a wonderful lens, really dig it but since I already own the 70-200 2.8 IS II, it's hard to pay roughly $4,000.00 more for a lens with the same focal length and considerably slower speed, just to gain servo. Servo is cool but not needed that often for me in 70-200. I didn't a find an appreciable difference in image quality between my $2k still lens and the $6k 70-200 T4.4 Same issue too, if I bought that lens, it is the prime sweet spot for interviews but I would rather not be constricted to lighting to a minimum T4.4 all of the time. Horses for courses.

For my own work, personally, I could get along fine with the 70-200 2.8 IS II and pairing it with the CN-E 18-80 T4.4 together. I mainly use the 70-200 for interviews where a servo isn't needed and the 18-80 would be for shoulder mounted and cradled verite' coverage that focal range is so handy, most of that type coverage is exteriors or well lit interiors for me.

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